block: introduce blk_init_flush and its pair

These two temporary functions are introduced for holding flush
initialization and de-initialization, so that we can
introduce 'flush queue' easier in the following patch. And
once 'flush queue' and its allocation/free functions are ready,
they will be removed for sake of code readability.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

6 files changed, 26 insertions, 8 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 6946a4275e6f..0a9d17269957 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -705,8 +705,7 @@ blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
         if (!q)
                 return NULL;
 
-        q->flush_rq = kzalloc(sizeof(struct request), GFP_KERNEL);
-        if (!q->flush_rq)
+        if (blk_init_flush(q))
                 return NULL;
 
         if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
@@ -742,7 +741,7 @@ blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
         return q;
 
 fail:
-        kfree(q->flush_rq);
+        blk_exit_flush(q);
         return NULL;
 }
 EXPORT_SYMBOL(blk_init_allocated_queue);
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 55028a707927..c72ab32fd8eb 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -472,7 +472,7 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
 }
 EXPORT_SYMBOL(blkdev_issue_flush);
 
-int blk_mq_init_flush(struct request_queue *q)
+static int blk_mq_init_flush(struct request_queue *q)
 {
         struct blk_mq_tag_set *set = q->tag_set;
 
@@ -485,3 +485,20 @@ int blk_mq_init_flush(struct request_queue *q)
                 return -ENOMEM;
         return 0;
 }
+
+int blk_init_flush(struct request_queue *q)
+{
+        if (q->mq_ops)
+                return blk_mq_init_flush(q);
+
+        q->flush_rq = kzalloc(sizeof(struct request), GFP_KERNEL);
+        if (!q->flush_rq)
+                return -ENOMEM;
+
+        return 0;
+}
+
+void blk_exit_flush(struct request_queue *q)
+{
+        kfree(q->flush_rq);
+}
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 78bcf8bfb22a..2758cdf2de94 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1859,7 +1859,7 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
 
         blk_mq_add_queue_tag_set(set, q);
 
-        if (blk_mq_init_flush(q))
+        if (blk_init_flush(q))
                 goto err_hw_queues;
 
         blk_mq_map_swqueue(q);
diff --git a/block/blk-mq.h b/block/blk-mq.h
index ecac69c08937..d567d5283ffa 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -27,7 +27,6 @@ struct blk_mq_ctx {
 
 void __blk_mq_complete_request(struct request *rq);
 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
-int blk_mq_init_flush(struct request_queue *q);
 void blk_mq_freeze_queue(struct request_queue *q);
 void blk_mq_free_queue(struct request_queue *q);
 void blk_mq_clone_flush_request(struct request *flush_rq,
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 17f5c84ce7bf..949075952119 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -517,11 +517,11 @@ static void blk_release_queue(struct kobject *kobj)
         if (q->queue_tags)
                 __blk_queue_free_tags(q);
 
+        blk_exit_flush(q);
+
         if (q->mq_ops)
                 blk_mq_free_queue(q);
 
-        kfree(q->flush_rq);
-
         blk_trace_shutdown(q);
 
         bdi_destroy(&q->backing_dev_info);
diff --git a/block/blk.h b/block/blk.h
index e515a285d4c9..c6fa3d4c6a89 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -22,6 +22,9 @@ static inline void __blk_get_queue(struct request_queue *q)
         kobject_get(&q->kobj);
 }
 
+int blk_init_flush(struct request_queue *q);
+void blk_exit_flush(struct request_queue *q);
+
 int blk_init_rl(struct request_list *rl, struct request_queue *q,
                 gfp_t gfp_mask);
 void blk_exit_rl(struct request_list *rl);